Alterations in the biosynthesis, secretion, and regulation of TSH and its subunits occur in patients with disorders of the thyroid-pituitary axis. To define these abnormalities, one must understand the molecular events involved in the biosynthesis of TSH and its subunits. TSH is one of a family of glycoprotein hormones that consists of two non-covalently linked, dissimilar subunits, designed alpha and beta. We propose to investigate the cellular events that take place in the biosynthesis of TSH. We wish to determine how these processes are regulated, how they may be interdependent, and how they may be involved in intracellular transport, packaging, and secretion of hormone. The isolation of mRNA coding for the TSH sununits and the production of cDNA to mRNA will allow study of the translational and transcriptional process. In addition, pulse-chase labeling experiments in intact cells will allow study of the post-translational processes. These initial studies will then provide the basis for subsequent studies of the cellular mechanisms involved in the regulation of subunit synthesis, assembly, and secretion mediated by thyrotropin-releasing hormone and thyroid hormones. We will also investigate TSH and subunit secretion in the normal thyrotroph using the bovine anterior pituitary cell culture systems. In our clinical approach, we will determine the long-term metabolic consequences of slight and variable decreases in the serum concentration of T4 and T3 and concomitant increases of TSH on: (a) cardiovascular system, (b) pituitary function and size (tumor), and (c) breast abnormalities, including breast cancer. We plan to expand our investigations of the unbalanced alpha sununit secretion by pituitary tumors in patients in order to evaluate the efficacy of subunit measurements in early diagnosis and effective therapy. In addition, immunochemical and physicochemical properties of subunits secreted by pituitary tumors will be evaluated to elucidate similarities or differences in the biosynthesis of the glycoprotein from normal and malignant pituitary cells.